Unitized face type seal

ABSTRACT

A primary face type seal is maintained in face to face engagement by secondary elastomer seals. A multi-part retainer encircles the primary and secondary seals to provide a unitizing housing for permanently locating the enclosed seals in appropriate alignment.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is concerned with improvements in face type seals andmore particularly with incorporation of the face type seals into aunitized housing.

2. Description of the Prior Art

Face type seals, also called rotary end face mechanical seals, generallyhave a primary seal comprised of a first and a second relatively stiffprimary sealing ring and a pair of secondary sealing or annularresistant rings generally of elastomeric material. The sealing ringshave abutting mating faces or surfaces that are highly polished hardsurfaced metallic faces which are lapped to extremely flat superfinefinish profiles. The secondary sealing members are positioned betweenadjacent housings and the back sides of the primary sealing rings. Onehousing is generally a stationary housing, for instance an axle housing,while the other housing is usually an internal bore in a rotatingmember, for instance a wheel hub.

The annular resilient rings serve a dual function. Firstly the resilientrings provide a loading force on the back side of the primary sealingrings to ensure good face to face contact and secondly the resilientrings provide a seal that prevents fluid flow from one side of theresilient rings to the other, either between one of thehousing/resilient ring margins or one of the sealing ring/resilient ringmargins.

U.S. Pat. Nos. 3,940,154 to Olsson and 3,241,843 to Hatch show typicalface type seals that are different from this invention but set forth thestate of the art.

Prior art seals have proven themselves effective in severe dutyenvironments where the seal is constantly exposed to dirt, grit anddust. Hence these face type seals lend themselves particularly well tooff highway construction equipment.

The need to maintain the superfine finish on the mating faces of thesealing rings is critical to good seal performance and life expectancy.It has been found that once the sealing rings and the accompanyingresilient rings are properly installed the sealing rings will performwell, however, if contamination is present on the superfine finishsurfaces of the sealing rings at the time of installation then the sealwill fail prematurely.

At least one solution to preventing the inclusion of dirt duringassembly is the use of a cellulose band, shown in the above mentionedHatch patent, that is shrunk around the outer periphery of the sealingrings at the time of manufacture. Subsequent to the installation of thejoined sealing rings the normal rotation of the adjoining housings willbreak the band which is then disintegrated.

The difficulty experienced with prior art face type sealing rings isthat there are two basic component sets each set including a primarysealing ring and an annular resilient ring. These two basic componentsets eventually are separated, either when the host structure isoverhauled or even earlier when the machine is being assembled (if theprior art patented band is not used). This separation of the two basiccomponent sets provides a chance for foreign matter to get between themating faces and ruin the seal.

Another difficulty with prior art face type seal sets is that as theyare independently installed in the host housings there is a chance ofmisalignment between them that will generate unequal loading around thefaces of the mating sealing rings. This unequal loading may also bedetrimental to the life expectancy of the seal.

It is among the objects of this invention to provide a face type sealthat has a unifying multi-part enclosure for containing the two basiccomponent sets.

Another object of the invention is to provide a face type seal that hasall its parts contained in a single unitized component.

Also an object is to provide a unitized face type seal that, as a singlecomponent, is constructed so as to prevent the inclusion ofcontamination between the sealing faces prior to installation.

Another object is to provide a face type seal that is arranged as aunitized component so as to ensure perfect alignment between the sealfaces before, during and after installation.

A further object of this invention is to provide a face type seal havingan installation location guide flange integral with the unitized faceseal component.

These and other objects and advantages of this invention will beapparent from the accompanying description and drawing figures.

SUMMARY OF THE INVENTION

A housing is provided to maintain the basic components of a face typeseal in a permanent position relative to each other. In one embodimentthe housing is made up of an interior shell, an exterior shell memberand a circumferential spacer. The interior shell is a generally annularmember having a base portion, a radially extending wall perpendicular tothe base portion and a transverse axially disposed upper portionperpendicular to the radially extending wall. A depth limitingprojection extends radially inwardly and perpendicularly from the baseportion of the interior shell. An elastomer coating may be bonded to theinside diameter of the interior shell.

The exterior shell of the housing is a circumferential ring having abroad, flat circumferential band section that is arranged outboard fromand concentrically to the base portion of the interior shell. Theexternal shell has radially projecting flange members at right angles tothe broad flat section thereof projecting inwardly toward the base ofthe interior shell.

A circumferential spacer, having an outside diameter equivalent to theinside diameter of the broad flat section of the exterior shell, ispositioned in the exterior shell during assembly.

The interior and exterior shell members provide the housing for the wellknown face type seals which are concentrically arranged between theexterior shell and the interior shell. The annular resilient rings abutthe outboard internal corner of the interior shell and the inwardlydirected flange and the circumferential spacer of the exterior shellrespectively to suspend the sealing members inside the unitized housing.

In a second embodiment of the unitized face type seal the depth limitingprojection is replaced with a projection on the radially extending wallof the interior shell. Furthermore, the exterior shell is formed havingthe broad flat circumferential band split into two levels so that thecircumferential spacer is eliminated. In the second embodiment anelastomeric seal is bonded to the outside diameter of the lesserdiameter section of the exterior shell to fulfill sealing and insulatingobjectives.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Several embodiments of this invention are shown in the drawing figureswherein:

FIG. 1 is a cross sectional view of a unitized face type seal carried ona non-rotating spindle;

FIG. 2 is a cross sectional view of an alternative embodiment of theunitized face type seal carried on a non-rotating spindle;

FIG. 3 is a cross sectioned view of a portion of the unitized face sealof FIG. 1;

FIG. 4 is a cross sectioned view of a portion of the unitized face sealof FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

A first embodiment of the invention is seen in FIGS. 1 and 3. Looking atthese figures the environment consists of a non-rotating axle or spindle10 having a reduced diameter portion 12 and a beveled step 14. Thespindle supports a wheel 16 through at least one bearing means 20.

The unitized face seal, generally 22, is carried on the larger portionof the spindle 10. Well known in the prior art are seal component setswhich include a first 24 and a second 26 sealing ring and a first 30 anda second 32 annular resilient ring. The sealing rings 24 and 26 areannular rings having divergently related generally radially and axiallyextending sufaces. The radial surfaces 34 and 36 are super fine finishsurfaces that provide primary sealing. Lubricating fluid or lubricatingthe bearings 20 will occupy the space below the axial portions of thesealing rings.

The resilient annular rings 30 and 32 are compressed between theunifying housing members and the back side of the sealing rings 24 and26 in order to press the sealing rings together into good contact and toseal the margins between the relatively non-rotating components.

The unifying structure is made up of an interior shell generally 40having a plurality of surfaces including a flat base 42, a radiallyextending wall 44 perpendicular to the base 42, a transverse axiallydisposed upper portion 46 perpendicular to the upwardly extending wall44 and extending back over the base 42 and a depth limiting tab 50.Bonded to the spindle side of the base 42 of the interior shellgenerally 40 is a laminate of elastomer material 48 which aids inmaintaining the interior shell in non-rotating engagement with thespindle.

The depth limiting projection or tab 50 is shown in contact with thebeveled step 14 of the spindle, thus movement of the interior shell tothe right in FIG. 1 is positively prevented.

An exterior shell, generally 52 is a circumferential ring having a broadflat circumferential band 54 outboard from the interior shell 40. Theexterior shell 52 has radially projecting flange members, first andsecond being 56 and 60 respectively, that project inwardly toward theinterior shell 40.

Carried on the inner surface of the exterior shell 52 is acircumferential spacer 62 extending from a first interior corner 64 partway across the inside surface of the exterior shell. The purpose of thisspacer is to equalize the distance between the base 42 surface and theinside diameter of the spacer 62 and the inside diameter of thetransverse axially disposed upper portion 46 of the interior shellgenerally 40. This enables the use of equal diameter annular resilientrings 30 and 32.

In FIG. 1 the exterior shell generally 52 appears to be displacedlaterally such that the second radially projecting flange member 60 isspaced away from the radially extending wall 44. The wheel 16 contactingthe exterior shell has pushed the exterior shell laterally such that adegree of preload or compression is exerted on the first 30 and second32 annular resilient rings so that the mating faces of the seals areurged together with designed force and leakage between the marginsaround each annular resilient sealing ring are tight enough to preventfluid leakage around them.

In FIG. 3 the same embodiment of the unitized face seal, generally 22,is shown. In this cross section view of a portion of the structure theseal is in an uncompressed state as it would be before installation.Notice that the second radially projecting flange member 60 is incontact with the radially extending wall 44 of the interior shellgenerally 40. This figure shows that alignment of the faces of thesealing rings 24 and 26 is maintained even when the unitized seal is "onthe shelf". Also since these faces are in contact with each other, theannular resilient rings 30 and 32 are under slight compression, there islittle chance that foreign matter can get between the faces. Theunitized face seal, as shown in FIG. 3, can be taken from stock andinstalled on a vehicle with good assurances that there will be noforeign matter between the mating faces and that the sealing rings willbe properly aligned (providing of course that the unitized face seal isproperly installed up to the depth limiting tab 50 and the wheel is puton squarely). On installation more compression will be transferred tothe annular resilient rings thus forcing the seal rings together moreforcefully.

FIGS. 2 and 4 portray a unitized face type seal similar to that alreadydescribed in the first embodiment. The non-rotating axle or spindle 10having the reduced diameter portion 12, and the beveled stop 14 betweenthe axle diameters, the wheel 16 and the bearing 20 are all familiarfrom FIG. 1.

The second embodiment unitized face type seal, generally 66, has aninner shell 70 having a base portion 72, a radially extending wall 74and an axially extending top portion 76 extending back over the baseportion 72. The radially extending wall 74 has a projection 80 at thejuncture of the base portion 72 and the radially extending wall 74. Theprojection 80 is used to limit the depth of the unitized face type sealand in this embodiment the projection takes the place of the depthlimiting tab 50 of FIG. 1.

An outer shell 82 is a generally circumferential band that has a firstsurface 84 and a second surface 86 providing two outer shell outsidedimensions with the first surface 84 having a greater outside diameter.A first radially projecting tab 90 and a second radially projecting tab92 extend from the circumferential surfaces 84 and 86 perpendicularlytoward the inner shell 70.

A seal 88 of elastomeric material encircles the outer shell around thesecond surface of the outer shell. This elastomeric seal 88 provides adual function of providing a seal between the wheel 16 and the unitizedface seal outer shell and also act as an insulator to insulate theunitized face seal from heat conducted through the wheel generatedduring braking of the wheel. This seal may also prevent rotation of theouter shell in the wheel.

A slightly revised cross sectional shape of the first and second annularresilient rings 94 and 96, is shown in this embodiment. Similarly, thecross sectional shape of the first and second seal rings 100 and 102 areslightly different in this embodiment. The cross sectional shape ofthese components is a matter of design choice.

Notice that in FIG. 4 the second embodiment of the face type sealgenerally 66 is shown in an uninstalled or relaxed position mode. Thedifference is that in FIG. 4 only minimal force is exerted on the matingfaces when it is in this relaxed condition. The faces are in contactthus assuring that under normal conditions no dirt will get between thefaces. As expected the outer shell 82 will be displaced laterally whenthe unitized seal is installed thus insuring increased force between theseal ring faces.

A thin film 104 of plastic is applied to the exterior side of the base72 of the inner shell 70 that, coupled with a slight press fit, willfill minute machining marks on the accompanying members, i.e. splindle10, which are often avenues of oil leakage.

The foregoing description has described two embodiments of unitized facetype seals each fulfilling various objects of the invention and settingforth advantages over the prior art. Although specific details have beenrecited it is expected that various nuances of design may be selected tooptimize the effectiveness of the invention. For instance various shapesof annular resilient rings and seal rings could be utilized withoutdeparting from the spirit and scope of the appended claims.

What is claimed is:
 1. A unitized face type seal comprising:a first anda second annular face type seal ring having axially and radiallyextending surfaces and flat engagement surfaces machined on saidradially extending surfaces; a first and a second annular resilient ringin contact with the nonengaging surfaces of said respective first andsaid second annular face type seal rings; an interior shell having abase portion, a radially extending wall and a transverse axiallydisposed upper portion for maintaining said second annular resilientring in position; an exterior shell having a circumferential bandportion and a first and a second radially projecting flange member, saidsecond radially projecting flange member extending toward said base ofsaid interior shell parallel to said radially extending wall of saidinterior shell; a circumferential spacer carried on the interior of saidexterior shell abutting said first radially projecting flange member,said circumferential spacer and said first radially projecting flangemember retaining said annular resilient ring in position whereby saidinterior shell, said exterior shell and said circumferential spacerprovide a unitized housing for supporting said first and second facetype seal rings through said first and second annular resilient rings inface to face contact and properly aligned relative to each other at alltimes.
 2. The invention in accordance with claim 1 wherein said interiorshell is provided with a depth limiting tab radially disposed inwardlyaway from said exterior shell location.
 3. The invention in accordancewith claim 1 wherein an elastomer coating is bonded to the innermostsurface of said base of said interior shell.
 4. The invention inaccordance with claim 1 wherein said exterior shell is restrained fromlateral movement in one direction relative to said interior shell bycontact between said second radially projecting flange member and saidradially extending wall of said interior shell.
 5. The invention inaccordance with claim 4 wherein said exterior shell is free to movelaterally in a direction increasing the space between said secondradially projecting flange member and said radially extending wall ofsaid interior shell.